When opened in 1903, the 1,600 foot long main span of the Williamsburg Bridge was the world's longest suspension span, surpassing the nearby Brooklyn Bridge by only 4.5 feet. The Williamsburg Bridge remained the world's longest suspension bridge span for 21 years until the opening of the Bear Mountain Bridge in 1924. The Williamsburg Bridge has two unsuspended side spans of 596.5 feet, each supported from below by trussed towers, giving the bridge an overall length of 2,793 feet. The four main suspension cables are 18.75 inches in diameter and each composed of over 10,000 wires.
Three rivers - the Allegheny, Monongahela, and Ohio - join in Pittsburgh, making the city a natural site for the building of bridges. But the Smithfield Street Bridge stands apart from other Pittsburgh bridges for several reasons: it replaced structures by two well-known bridge engineers, Lewis Wernwag and John A. Roebling; it was the first use in America of the lenticular - or lens-shaped - truss design; and it was one of the first major bridges in the U.S. built primarily with steel.
When opened in 1909, the Queensboro Bridge had the two longest steel cantilever spans in the world - 1,182 feet from Manhattan to Blackwell's Island and 984 feet from Blackwell's Island to Queens. These would remain the world's longest cantilever spans until the completion of the Quebec Bridge in 1917. The Queensboro Bridge has an overall length of 3,724.5 feet. It originally carried two elevated railway lines, two trolley lines, six carriage lanes and two pedestrian walkways.
In the 1850s, the Lexington and Danville Railroad began building a suspension bridge over the Kentucky River. The bridge was designed by John A Roebling. Due to unforeseen increases in train loads, the Roebling bridge was never completed. The High Bridge would then be built 20 years later on the existing foundations.